As phytoplasmas are located inside the phloem tissue, always surrounded by numerous layers of other cells,
they can result difficult candidates for microscopical investigations. Moreover, the necessity to kill the plant
tissues for microscopy observations causes instantaneous and irreversible modifications in the sieve elements,
leading to misleading information and erroneous interpretations. Phytoplasmas were here investigated
in intact Vicia faba host plants using DAPI as fluorescent probe and confocal laser scanning
microscopy. The described nondestructive technique may be applied for the imaging of phytoplasmas
and of different pathogen-related responses in planta.
